Mount for electron discharge devices



Nov. 27, 1934. REED 1,982,069

MOUNT FOR ELECTRON DISCHARGE DEVICES Filed Nov. 29, 1953 INVENTOR $TANLEY M.REED

Patented Nov; 27, 1934 UNITED STATES MOUNT FOE ELECTRON DISCHARGE DEVICES Stanley M. Reed, Summit, N. 1., aaaignor to Radio Corporation of America, a corporation of Delaware Application November 29, 1933, Serial No. 700,179

Claims. (Cl. 250-215) My invention relates to improvements in electron discharge devices and more particularly to improved means for firmly and accurately positioning the electrode mount within the envelope 6 of the tube.

In modern tubes, such as a tube having the dome type envelope, it is found desirable to firmly hold the electrode assembly in the envelope to prevent transverse movement. To this end the 10 dome or other constricted portion of the tube is utilized to steady the electrode assembly against transverse vibration and to keep the assembly more firmly established in position than when the assembly is supported and steadied only from 16 the stem press. When steadied in this manner, it is desirable to use supporting means which will steady the mount sufiiciently to avoid noises such as clicking, which is caused by contact between the electrode assembly and the envelope 20 when the tube is jarred or vigorously vibrated, and which is sufficiently resilient to avoid stresses and distortion of the mount assembly which are produced when a mount provided with rigid supporting means, is forced into the dome of a slightly smaller than the usual size bulb. Attempts to steady the mount by metal braces which touch the bulb have not been successful, as such braces produce strain checks and cracks in the glass at points where the metal touches the glass.

The principal object of my invention is to firmly hold and accurately position the free end of an electrode mount within the envelope of an electron discharge device by flexible means attached to the mount and firmly engaging the interior walls of the envelope without producing a deleterious effect on the mount or on the walls of the envelope or injuring the envelope in any way during exhaust.

The novel features which I believe to be characteristic of my invention are set forth with particularity in the appended claims, but the invention itself will best be understood by reference to the following description taken in connection with the accompanying drawing, in which:

Figure l is a view in perspective and partly broken away of an electron discharge device embodying my invention.

Figure 2 is an enlarged plan view of a mica spacer and support shown in Figure 1 and made in accordance with my invention;

Figure 3 is an enlarged portion of the mica spacer shown in Figin'e 2, to show details of my invention;

Figure 4 is a modification of a mica spacer made in accordance with my invention;

Figure 5 shows a still further modification of a mica spacer made in accordance with my invention.

The electron discharge device shown in Figure 1 has the usual base 10 on a dome type bulb 11 80 with the usual stem and press 12. The mount 13 comprises the electrode assembly and extends within the extended tubular portion or dome of the bulb 11. On the upper end of the electrode assembly there is secured by straps 14 welded to 85 the mount a mica electrode spacer and support 15, shown as'a disc in Figures 1, 2, and 3, and extending transversely of the mount and of the tubular portion or dome of the envelope 11.

Due to the fact that the envelopes are not all of exactly the same diameter, rigid spacers on the upper end of the mount to fit snugly in the dome are not feasible. If the spacer is rigid and fits the largest envelopes, the mounts will be stressed and distorted when a smaller envelope is placed over the mount assembly, while if the spacer fits the smaller envelopes, it will be loose in the larger envelopes and clicking will result.

In accordance with my invention I provide the spacer 15 with flexible fingers or projections 16 and 17 which extend radially from the edge of the spacer some of which at least contact the inner walls of the dome of the envelope 11 to firmly support or steady the mount and center it in the envelope. The fingers are of different lengths, and preferably the alternate fingers are long and short. At the short fingers 16 the spacer has a radius equal to the radius of the dome of a bulb of diameter, and at the long fingers 1'7 a radius equal to or slightly greater than the radius of the dome of a bulb of maximum diameter, hence the spacer will make contact through some of the fingers with the wall of any bulb used. The flexible mica fingers 16 and 17 are still? enough to steady the mount, but will not cause harmful stresses or distortion of the mount. It is obvious that the entire rim of the spacer could be provided with fingers, and that the fingers could all be of a length which gives the spacer a diameter equal to or slightly greater than the maximum inner diameter of the bulbs.

One specific type of mica spacer 15 made as shown in Figures 1 and 2 and successfully used in commercial tubes is made of sheet mica from .008 inch to .015 inch in thickness, has a diameter of about .975 inch, and has short fingers 16 about .040 inch in length and long fingers 1'7 about .045 inch in length. In such a spacer the diameter from tip to tip of a pair of long fingers is 1.055 inches and of a pair of short fingers cent the outside side rods of the mount and thereby lessen the tendency of the mica spacer to tilt when the bulb is slid down over the mount during the assembling of the tube. When the bulb is placed over the mount some of the fingers may be flexed downward slightly and to an extent dependent on the inner diameter of the dome of the bulb. These flexed fingers resiliently center the electrode assembly firmly and accurately within the envelope and prevent clicking in the tube.

In Figure 4 the mica spacer 18 has the general shape of a Greek cross, with four arms 19, each of which has its edge provided with fingers 20 which are in this case all of the same length, about .040 inch for micas about 1 inch in diameter and from .008 inch to .015 inch in thickness.

This type of mica spacer has the same mode of operation as that shown in Figure 2.

In Figure 5 the mica spacer 21 is ring-shaped, and has on its rim four groups of resilient projections or fingers 22. This mica spacer also has the same functions as the spacer shown in'Figures 2 and 4.

While I have indicated the preferred embodiments of my invention of which I am now aware and have also indicated specific applications for which my invention may be employed, it will be apparent that my invention is not limited to the exact forms illustrated or the use indicated, but that many variations may be made in the particular structure used and the purpose for which it is employed without departing from the scope of my invention, as set forth in the appended claims.

What I claim as new is,-

1. An envelope having an extended tubular portion, a mount comprising an electrode assembly positioned in said envelope and at least in part within said tubular portion, a fiat mica spacer secured to said mount to extend transversely of said tubular portion, and having its edges formed to provide flexible projections extending into engagement with the walls of the extended tubular portion of said envelope whereby they are flexed to resiliently support said mount in a predetermined position within the tubular portion of said envelope.

2. An electron discharge device provided with an envelope having an extended tubular portion, a mount comprising an electrode assembly positioned in said envelope and extending within said tubular portion, a flat mica spacer secured to said mount to extend transversely of the tubular portion of said envelope and provided with flexible fingers at opposite edges for contacting the interior wall 01' said tubular portion whereby they are flexed to resiliently and firmly support said mount in a predetermined position within the extended tubular portion of said envelope.

3. An electron discharge device provided with an envelope having an extended tubular portion, a mount comprising an electrode assembly positioned in said envelope and extending within said tubular portion, a mica disc spacer secured to said mount to extend transversely of said tubular portion and provided with flexible fingers, alternate fingers being slightly shorter than the others, said fingers engaging walls of the tubular portion of said envelopetofirmly and resiliently support said mount in a predetermined position within the extended tubular portion of said envelope.

4. An electron discharge device provided with an envelope having an extended tubular portion,

a. mount comprising an electrode assembly positioned in said envelope and extending coaxially of and within the tubular portion, a flat mica spacer having arms extending outwardly from said mount within and transversely of said tubular'portion, said arms being formed at their ends to provide flexible lingers in engagement with the interior wall of said extended tubular portion to firmly support said mount within said. envelope.

5. An electron discharge device provided with an envelope having an extended tubular portion at one end thereof, a mount comprising an electrode assembly mounted in the other end of said envelope and extending within and coaxially of said tubular portion, a fiat mica spacer secured to said mount within the tubular portion of the envelope to extend transversely of said mount, and flexible fingers extending from the edgesv of said fiat mica spacer, the diameter of the spacer at the tips of the fingers being greater than the diameter of the extended tubular portion of said envelope so that said fingers engage the walls of the extended tubular portion of the envelope whereby they are fiexed to resiliently and firmly support the mount in a predetermined position within said envelope.

STANLEY M. REED. 

